Returns from a PSM line peptide sequence,
    and other information about the PSM.
    Return values:
        specfn          -   str
        psm_id 	 	-   str
        scan            -   str
        peptideseq      -   str
        score		-   str

def get_psm(line, unroll=False, specfncol=None):
    """Returns from a PSM line peptide sequence,
    and other information about the PSM.
    Return values:
        specfn          -   str
        psm_id 	 	-   str
        scan            -   str
        peptideseq      -   str
        score		-   str
    """
    if specfncol is None:
        specfncol = mzidtsvdata.HEADER_SPECFILE
    specfn = line[specfncol]
    psm_id = get_psm_id(line)
    scan = line[mzidtsvdata.HEADER_SCANNR]
    peptideseq = get_psm_sequence(line, unroll)
    score = line[mzidtsvdata.HEADER_MSGFSCORE]
    return specfn, psm_id, scan, peptideseq, score