def __call__(self, match):
original = match.string<EOL>key = match.group(Constants.KEY_GROUP)<EOL>replacement = self.params.get(key)<EOL>if replacement is None:  <EOL><INDENT>replaced = original<EOL><DEDENT>else:<EOL><INDENT>start, end = match.span(Constants.VALUE_GROUP)<EOL>if start < <NUM_LIT:0>:<EOL><INDENT>start = end = len(original.rstrip())<EOL><DEDENT>self.missing.remove(key)<EOL>replaced = "<STR_LIT>".join([original[:start], str(replacement), original[end:]])<EOL><DEDENT>return replaced<EOL>
Given a regex Match Object, return the entire replacement string