def _get_sample_names(input_vcf):
    """Returns list of sample names from input VCF"""
    with open(input_vcf, 'r') as input_file:
        column_header = None
        sample_names = []
        for line in input_file.readlines():
            if not line.startswith('##'):
                if line.startswith('#'):
                    column_header = line.rstrip()
                    column_fields = column_header.split('\t')
                    n = len(column_fields)
                    sample_names = column_fields[9:n + 1]
        return sample_names
