How to use the comparem.common.check_file_exists function in comparem

def __init__(self, filename):
        """Initialization.

        Parameters
        ----------
        filename : str
            GFF file to parse.
        """
        check_file_exists(filename)

        self.genes = {}
        self.last_coding_base = {}

        self.__parseGFF(filename)

        self.coding_base_masks = {}
        for seq_id in self.genes:
            self.coding_base_masks[seq_id] = self.__build_coding_base_mask(seq_id)