following optional packages may be useful: • pycurl is used by the optional tornado.curl_httpclient. Libcurl version 7.22 or higher is required. • pycares is an alternative non-blocking DNS resolver that can recent version of libcurl and pycurl. Currently the minimum supported version of libcurl is 7.22.0, and the minimum version of pycurl is 7.18.2. It is highly recommended that your libcurl installation is encounter various problems with request timeouts (for more information, see http://curl.haxx.se/ libcurl/c/curl_easy_setopt.html#CURLOPTCONNECTTIMEOUTMS and comments in curl_httpclient.py). To select curl_httpclient

packages may be useful:pycurl [http://pycurl.io/] is used by the optional tornado.curl_httpclient. Libcurl version 7.22 or higher is required. pycares [https://pypi.org/project/pycares/] is an alternative recent version of libcurl and pycurl. Currently the minimum supported version of libcurl is 7.22.0, and the minimum version of pycurl is 7.18.2. It is highly recommended that your libcurl installation is encounter various problems with request timeouts (for more information, see http://curl.haxx.se/libcurl/c/curl_easy_setopt.html#CURLOPTCONNECTTIMEOUT MS and comments in curl_httpclient.py). To select

. . . . . . . . 1171 71 Future 1172 72 Interactive Utilities 1173 73 Lazy Artifacts 1181 74 LibCURL 1182 75 LibGit2 1183 76 Dynamic Linker 1224 77 Linear Algebra 1227 77.1 Special matrices . . callback should handle a total size of zero gracefully. If the verbose option is set to true, libcurl, which is used to implement the download functionality will print debugging information to stderr original URL that was requested without any redirects • code: the libcurl error code; 0 if a protocol-only error occurred • message: the libcurl error message indicating what went wrong • response: response

. . . . . . . . 1171 71 Future 1172 72 Interactive Utilities 1173 73 Lazy Artifacts 1181 74 LibCURL 1182 75 LibGit2 1183 76 Dynamic Linker 1224 77 Linear Algebra 1227 77.1 Special matrices . . callback should handle a total size of zero gracefully. If the verbose option is set to true, libcurl, which is used to implement the download functionality will print debugging information to stderr original URL that was requested without any redirects • code: the libcurl error code; 0 if a protocol-only error occurred • message: the libcurl error message indicating what went wrong • response: response

. . . . . . . . 1366 73 Future 1368 74 Interactive Utilities 1369 75 Lazy Artifacts 1379 76 LibCURL 1380 77 LibGit2 1381 78 Dynamic Linker 1429 79 Linear Algebra 1433 79.1 Special matrices . . callback should handle a total size of zero gracefully. If the verbose option is set to true, libcurl, which is used to implement the download functionality will print debugging information to stderr original URL that was requested without any redirects • code: the libcurl error code; 0 if a protocol-only error occurred • message: the libcurl error message indicating what went wrong • response: response

. . . . . . . . 1366 73 Future 1368 74 Interactive Utilities 1369 75 Lazy Artifacts 1379 76 LibCURL 1380 77 LibGit2 1381 78 Dynamic Linker 1429 79 Linear Algebra 1433 79.1 Special matrices . . callback should handle a total size of zero gracefully. If the verbose option is set to true, libcurl, which is used to implement the download functionality will print debugging information to stderr original URL that was requested without any redirects • code: the libcurl error code; 0 if a protocol-only error occurred • message: the libcurl error message indicating what went wrong • response: response

. . . . . . . . 1366 73 Future 1368 74 Interactive Utilities 1369 75 Lazy Artifacts 1379 76 LibCURL 1380 77 LibGit2 1381 78 Dynamic Linker 1429 79 Linear Algebra 1433 79.1 Special matrices . . callback should handle a total size of zero gracefully. If the verbose option is set to true, libcurl, which is used to implement the download functionality will print debugging information to stderr original URL that was requested without any redirects • code: the libcurl error code; 0 if a protocol-only error occurred • message: the libcurl error message indicating what went wrong • response: response

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1437 77 Lazy Artifacts 1440 78 LibCURL 1441 79 LibGit2 1442 80 Dynamic Linker 1490 81 Linear Algebra 1494 81.1 Special matrices . . callback should handle a total size of zero gracefully. If the verbose option is set to true, libcurl, which is used to implement the download functionality will print debugging information to stderr original URL that was requested without any redirects • code: the libcurl error code; 0 if a protocol-only error occurred • message: the libcurl error message indicating what went wrong • response: response

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1435 77 Lazy Artifacts 1438 78 LibCURL 1439 79 LibGit2 1440 80 Dynamic Linker 1488 81 Linear Algebra 1492 81.1 Special matrices . . callback should handle a total size of zero gracefully. If the verbose option is set to true, libcurl, which is used to implement the download functionality will print debugging information to stderr original URL that was requested without any redirects • code: the libcurl error code; 0 if a protocol-only error occurred • message: the libcurl error message indicating what went wrong • response: response

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1434 77 Lazy Artifacts 1437 78 LibCURL 1438 79 LibGit2 1439 80 Dynamic Linker 1487 81 Linear Algebra 1491 81.1 Special matrices . . callback should handle a total size of zero gracefully. If the verbose option is set to true, libcurl, which is used to implement the download functionality will print debugging information to stderr original URL that was requested without any redirects • code: the libcurl error code; 0 if a protocol-only error occurred • message: the libcurl error message indicating what went wrong • response: response