#----------------------------------------------------------------------
# (C) Monday, January 29, 2018 -- Dr. William T. Verts
#
# This third version solves the "duplicate code" problem by writing
# a function to be used/called in each case.  The GetNumber function is
# designed to return a number which is 0 or positive, BUT it has to
# tell the user what value is expected.  Is it Number #1 or Number #2?
# That is the purpose of the parameter Response, which is a placeholder
# for a string passed in from the main program.  Whatever value of
# Response is passed in, that is what shows up during the invocation of
# the input functions.  That is, the formal parameter Response is used
# as an actual parameter to input.  In the main program, the strings
# "Enter Number #1 --- " and "Enter Number #2 --- " are the actual
# parameter values passed in to Response.  The value N passed back by
# the return statement is saved in N1 or N2, as appropriate.
#----------------------------------------------------------------------

def GetNumber (Response):
    N = input(Response)
    while (N < 0):
        print "This is not a positive number"
        N = input(Response)
    return N

N1 = GetNumber("Enter Number #1 --- ")
N2 = GetNumber("Enter Number #2 --- ")
A = (N1 + N2) / 2.0
print "The average is: ", A