<SYSTEM_TASK:>
Solve the following problem using Python, implementing the functions described below, one line at a time
<END_TASK>
<USER_TASK:>
Description:
 def variant_overlaps_interval( variant_start, n_ref_bases, interval_start, interval_end):
 """ Does a variant overlap a given interval on the same chromosome? Parameters variant_start : int Inclusive base-1 position of variant's starting location (or location before an insertion) n_ref_bases : int Number of reference bases affect by variant (used to compute end coordinate or determine whether variant is an insertion) interval_start : int Interval's inclusive base-1 start position interval_end : int Interval's inclusive base-1 end position """


    if n_ref_bases == 0:
        # insertions only overlap intervals which start before and
        # end after the insertion point, they must be fully contained
        # by the other interval
        return interval_start <= variant_start and interval_end >= variant_start
    variant_end = variant_start + n_ref_bases
    """
    if self._changes_exonic_splice_site(
            strand_ref,
            strand_alt,)
    """
    # overlap means other interval starts before this variant ends
    # and the interval ends after this variant starts
    return interval_start <= variant_end and interval_end >= variant_start