code: def range_intersect(a, b, extend=0):
      
      a_min, a_max = a
      if a_min > a_max:
          a_min, a_max = a_max, a_min
      b_min, b_max = b
      if b_min > b_max:
          b_min, b_max = b_max, b_min
  
      if a_max + extend < b_min or b_max + extend < a_min:
          return None
      i_min = max(a_min, b_min)
      i_max = min(a_max, b_max)
      if i_min > i_max + extend:
          return None
  
      return [i_min, i_max]
docs: Returns the intersection between two reanges.
  
      >>> range_intersect((30, 45), (55, 65))
      >>> range_intersect((48, 65), (45, 55))
      [48, 55]