strip transcript versions from a FASTA file. these appear like this:
    >ENST00000434970.2 cdna chromosome:GRCh38:14:22439007:22439015:1 etc

def strip_transcript_versions(fasta, out_file):
    """
    strip transcript versions from a FASTA file. these appear like this:
    >ENST00000434970.2 cdna chromosome:GRCh38:14:22439007:22439015:1 etc
    """
    if file_exists(out_file):
        return out_file
    with file_transaction(out_file) as tx_out_file:
        with open(tx_out_file, "w") as out_handle:
            with open(fasta) as in_handle:
                for line in in_handle:
                    if line.startswith(">"):
                        out_handle.write(line.split(" ")[0].split(".")[0] + "\n")
                    else:
                        out_handle.write(line)
    return out_file