#------------------------------------------------------------------------------ 
#  Swap.py
#  swap two elements in a list
#------------------------------------------------------------------------------

def swap(L, i, j):
   """exchange L[i] with L[j]"""
   temp = L[i]
   L[i] = L[j]
   L[j] = temp
# end swap()


# function main() -------------------------------------------------------------
def main():
   
   A = [4, 6, 2, 9, 6, -4, 1]

   print(A)
   swap(A, 3, 6)
   print(A)

# end main()


if __name__=='__main__':

   main()

# end