from typing import List
from typing import Tuple


def _edge_sequence (lst : List[int]) -> List[Tuple[int,int]]:
    """
    This method, given a sequence of picking positions formalised as a sequence of locations (origin excluded),
    generates a solution formalised by using tuples where each tuple represents an edge part of the solution.
    The resulting formalisation is the same used by Zhong.
    During this process the original list <lst> is not modified.


    :param lst: The picking list
    :return: The picking list formalised according to Zhong's guidelines

    """
    lst_c = list(lst)
    lst_c.insert(0,0)
    lst_c.append(0)
    return [(lst_c[i], lst_c[i + 1]) for i in range (len(lst_c) - 1)]