Replaces a sequence with another. Typically not useful but I use it in the ResidueRelatrix to make sure that the FASTA and SEQRES sequences match.

def replace_sequence(self, pdb_ID, chain_id, replacement_sequence):
        '''Replaces a sequence with another. Typically not useful but I use it in the ResidueRelatrix to make sure that the FASTA and SEQRES sequences match.'''
        old_sequences = self.sequences
        old_unique_sequences = self.unique_sequences
        self.sequences = []
        self.unique_sequences = {}
        for s in old_sequences:
            if s[0] == pdb_ID and s[1] == chain_id:
                self._add_sequence(pdb_ID, chain_id, replacement_sequence)
            else:
                self._add_sequence(s[0], s[1], s[2])

        self._find_identical_sequences()