def fun_lin(x, a, b):
    y = a*x + b
    print('x_locvar_fun_lin =', x)
    print('in_globvar_fun_lin =', x_in)
    return y


p0 = 2.5
p1 = 3.0
x_in = 10.0

out = fun_lin(x_in, p0, p1)

print('in_globvar_mainprog =', x_in)
print('x_locvar_mainprog =', x)