def is_aa_seq(file):
    """check input gene files to make sure they are amino acid sequences and not nucletotide sequences"""
    with open(file, 'r') as infile:
        all_count, atcg_count = 0, 0
        for line in infile:
            if line.startswith('>'):
                pass
            else:
                all_count += len(line)
                atcg_count += line.upper().count('A') + line.upper().count('T'
                    ) + line.upper().count('C') + line.upper().count('G')
        atcg_per = atcg_count / all_count
        if atcg_per > 0.7:
            return False
        else:
            return True
