<SYSTEM_TASK:>
Solve the following problem using Python, implementing the functions described below, one line at a time
<END_TASK>
<USER_TASK:>
Description:
 def _filter_by_statement(self, statement):
 """Filter the data collection based on a conditional statement."""

        self.__class__._check_conditional_statement(statement, 1)
        _filt_values, _filt_datetimes = [], []
        for i, a in enumerate(self._values):
            if eval(statement, {'a': a}):
                _filt_values.append(a)
                _filt_datetimes.append(self.datetimes[i])
        return _filt_values, _filt_datetimes