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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 bracketedList(l, r, sep, expr, allow_missing_close=False):
 """Parse bracketed list. Empty list is possible, as is a trailing separator. """

  # We may need to backtrack for lists, because of list comprehension, but not for
  # any of the other lists
  strict = l != '['
  closer = sym(r) if not allow_missing_close else p.Optional(sym(r))
  if strict:
    return sym(l) - listMembers(sep, expr) - closer
  else:
    return sym(l) + listMembers(sep, expr) + closer