<SYSTEM_TASK:>
Solve the following problem using Python, implementing the functions described below, one line at a time
<END_TASK>
<USER_TASK:>
Description:
 def _precompile_substitution(self, kind, pattern):
 """Pre-compile the regexp for a substitution pattern. This will speed up the substitutions that happen at the beginning of the reply fetching process. With the default brain, this took the time for _substitute down from 0.08s to 0.02s :param str kind: One of ``sub``, ``person``. :param str pattern: The substitution pattern. """

        if pattern not in self._regexc[kind]:
            qm = re.escape(pattern)
            self._regexc[kind][pattern] = {
                "qm": qm,
                "sub1": re.compile(r'^' + qm + r'$'),
                "sub2": re.compile(r'^' + qm + r'(\W+)'),
                "sub3": re.compile(r'(\W+)' + qm + r'(\W+)'),
                "sub4": re.compile(r'(\W+)' + qm + r'$'),
            }