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Solve the following problem using Python, implementing the functions described below, one line at a time
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Description:
 def initial_variant_sequences_from_reads( variant_reads, max_nucleotides_before_variant=None, max_nucleotides_after_variant=None):
 """ Get all unique sequences from reads spanning a variant locus. This will include partial sequences due to reads starting in the middle of the sequence around around a variant. """

    unique_sequence_groups = group_unique_sequences(
        variant_reads,
        max_prefix_size=max_nucleotides_before_variant,
        max_suffix_size=max_nucleotides_after_variant)

    return [
        VariantSequence(
            prefix=prefix,
            alt=alt,
            suffix=suffix,
            reads=reads)
        for ((prefix, alt, suffix), reads)
        in unique_sequence_groups.items()
    ]