<SYSTEM_TASK:>
Solve the following problem using Python, implementing the functions described below, one line at a time
<END_TASK>
<USER_TASK:>
Description:
 def is_gene_list(bed_file):
 """Check if the file is only a list of genes, not a BED """

    with utils.open_gzipsafe(bed_file) as in_handle:
        for line in in_handle:
            if not line.startswith("#"):
                if len(line.split()) == 1:
                    return True
                else:
                    return False