def get_minim_aminochain(PeptideSeq):
    """
    The function return length of minimum fragment of core peptide chain.

    Parameters
    ----------
    PeptideSeq : dict
        Core peptide chains for different biosynthesis types (e.g. A, B, or C).
    Returns
    -------
    min(lens_of_varints) : int
        Minimal possible lenght from possible variants.
    """
    lens_of_varints = []

    for bios_path in PeptideSeq:
        for var in PeptideSeq[bios_path]:
            
            len_of_varint_seq = 0

            for cont in PeptideSeq[bios_path][var]:

                len_of_varint_seq += len(cont)

            lens_of_varints.append(len_of_varint_seq)

    return  min(lens_of_varints) # Return minimal lenght from possible variants