def forget_subject(sid):
sub = subject(sid)<EOL>if sub.path in subject._cache:<EOL><INDENT>del subject._cache[sub.path]<EOL><DEDENT>else:<EOL><INDENT>for (k,v) in six.iteritems(subject._cache):<EOL><INDENT>if v is sub:<EOL><INDENT>del subject._cache[k]<EOL>break<EOL><DEDENT><DEDENT><DEDENT>return None<EOL>
forget_subject(sid) causes neuropythy's hcp module to forget about cached data for the subject
  with subject id sid. The sid may be any sid that can be passed to the subject() function.

This function is useful for batch-processing of subjects in a memory-limited environment; e.g.,
if you run out of memory while processing hcp subjects it is possibly because neuropythy is
caching all of their data instead of freeing it.