Where is the sourcecode for curl_easy_perform() in libcurl?

I cannot find the source code for this important function in the libcurl source tree. Nor do I find a definition of this function in curl.h. Neither a search of the linux kernel github source nor several google searches yields anything.

curl_easy_perform() has to be defined and implemented somewhere, or at least defined by way of some macro(?), but, while numerous examples are given of this function being called, I have found nothing of its implementation. Any ideas?