integer function multiply(a, b)
  integer, intent(in) :: a, b
  multiply = a * b
  
  
integer function addtwo(a, b)
  integer, intent(in) :: a, b
  addtwo = a + b
  
  
$ gfortran -shared -fPIC -g -o mult.so mult.f90
$ gfortran -shared -fPIC -g -o add.so add.f90


$ nm -ao mult.so | grep multiply
mult.so:00000000000005cc T multiply_


$ python3 testfunc.py
8
6


$ python3 -m numpy.f2py secret.f90 -m secretcode -h secret.pyf


$ python3 -m numpy.f2py -c secret.pyf secret.f90


$ ls -s
total 120
112 secretcode.cpython-37m-x86_64-linux-gnu.so    4 secret.f90    4 secret.pyf


$ f2py --f90flags=-fopenmp -L/usr/lib/gcc/x86_64-redhat-linux/4.8.2/ -lgomp -c -m test test.f90


$ python3 test1.py
 hello world. The secret number is    6