def is_deletion(self):
        """
        Does this variant represent the deletion of nucleotides from the
        reference genome?
        """
        # A deletion would appear in a VCF like CT>C, so that the
        # reference allele starts with the alternate nucleotides.
        # This is true even in the normalized case, where the alternate
        # nucleotides are an empty string.
        return (len(self.ref) > len(self.alt)) and self.ref.startswith(self.alt)
Does this variant represent the deletion of nucleotides from the
        reference genome?