How to use the pyfaidx.__init__.Sequence function in pyfaidx

) < end - start0 and self.default_seq:  # Pad missing positions with default_seq
            pad_len = end - start0 - len(seq)
            seq = ''.join([seq, pad_len * self.default_seq])
        else:  # Return less than requested range
            end = start0 + len(seq)

        if self.sequence_always_upper:
            seq = seq.upper()

        if not self.one_based_attributes:
            start = start0

        if self.as_raw:
            return seq
        else:
            return Sequence(
                name=rname, start=int(start), end=int(end), seq=seq)

If rc is set, reverse complement will be returned.
        """
        # Get sequence for all intervals
        chunks = [self.faidx.fetch(name, s, e) for s, e in intervals]
        start = chunks[0].start
        end = chunks[-1].end

        # reverce complement
        if rc:
            seq = "".join([(-chunk).seq for chunk in chunks[::-1]])
        else:
            seq = "".join([chunk.seq for chunk in chunks])

        # Sequence coordinate validation wont work since
        # len(Sequence.seq) != end - start
        return Sequence(name=name, seq=seq, start=None, end=None)

def unpadded_len(self):
        """ Returns the length of the contig without 5' and 3' N padding.
        Functions the same as contigNonNSize in Fasta.cpp at
        https://github.com/Illumina/hap.py/blob/master/src/c%2B%2B/lib/tools/Fasta.cpp#L284
        """
        length = len(self)
        stop = False
        for line in iter(self):
            if stop:
                break
            if isinstance(line, Sequence):
                line = line.seq
            for base in line.upper():
                if base == 'N':
                    length -= 1
                else:
                    stop = True
                    break
        stop = False
        for line in reversed(self):
            if stop:
                break
            if isinstance(line, Sequence):
                line = line.seq
            for base in line.upper():
                if base == 'N':
                    length -= 1