def _select_phase_left_bound(self, epoch_number):
idx = bisect.bisect_left(self.ladder, epoch_number)<EOL>if idx >= len(self.ladder):<EOL><INDENT>return len(self.ladder) - <NUM_LIT:1><EOL><DEDENT>elif self.ladder[idx] > epoch_number:<EOL><INDENT>return idx - <NUM_LIT:1><EOL><DEDENT>else:<EOL><INDENT>return idx<EOL><DEDENT>
Return number of current phase.
Return index of first phase not done after all up to epoch_number were done.