def fetch_seq_pygr(chr, start, end, strand, genome):
    """Fetch a genmoic sequence upon calling `pygr`
    `genome` is initialized and stored outside the function

    Parameters
    ----------
    chr : str
        chromosome
    start : int
        start locus
    end : int
        end locuse
    strand : str
        either '+' or '-'

    Returns
    --------
    seq : str
        genomic sequence in upper cases
    """
    try:
        seq = genome[chr][start:end]
        if strand == "-":
            seq = -seq
    except Exception as e:
        raise Exception('pygr cannot fetch sequences; %s' % e)
    return str(seq).upper()