Parse breakend and return tuple with results, parameters for BreakEnd
    constructor

def parse_breakend(alt_str):
    """Parse breakend and return tuple with results, parameters for BreakEnd
    constructor
    """
    arr = BREAKEND_PATTERN.split(alt_str)
    mate_chrom, mate_pos = arr[1].split(":", 1)
    mate_pos = int(mate_pos)
    if mate_chrom[0] == "<":
        mate_chrom = mate_chrom[1:-1]
        within_main_assembly = False
    else:
        within_main_assembly = True
    FWD_REV = {True: record.FORWARD, False: record.REVERSE}
    orientation = FWD_REV[alt_str[0] == "[" or alt_str[0] == "]"]
    mate_orientation = FWD_REV["[" in alt_str]
    if orientation == record.FORWARD:
        sequence = arr[2]
    else:
        sequence = arr[0]
    return (mate_chrom, mate_pos, orientation, mate_orientation, sequence, within_main_assembly)