code: def _revs_equal(rev1, rev2, rev_type):
      '''
      Shorthand helper function for comparing SHA1s. If rev_type == 'sha1' then
      the comparison will be done using str.startwith() to allow short SHA1s to
      compare successfully.
  
      NOTE: This means that rev2 must be the short rev.
      '''
      if (rev1 is None and rev2 is not None) \
              or (rev2 is None and rev1 is not None):
          return False
      elif rev1 is rev2 is None:
          return True
      elif rev_type == 'sha1':
          return rev1.startswith(rev2)
      else:
          return rev1 == revf _revs_equal(rev1, rev2, rev_type):
      '''
      Shorthand helper function for comparing SHA1s. If rev_type == 'sha1' then
      the comparison will be done using str.startwith() to allow short SHA1s to
      compare successfully.
  
      NOTE: This means that rev2 must be the short rev.
      '''
      if (rev1 is None and rev2 is not None) \
              or (rev2 is None and rev1 is not None):
          return False
      elif rev1 is rev2 is None:
          return True
      elif rev_type == 'sha1':
          return rev1.startswith(rev2)
      else:
          return rev1 == rev2
docs: Shorthand helper function for comparing SHA1s. If rev_type == 'sha1' then
      the comparison will be done using str.startwith() to allow short SHA1s to
      compare successfully.
  
      NOTE: This means that rev2 must be the short rev.