GOOD PRACTICE:

  A user could choose to not include the header <toolbox.hdr>.

  Therefore, when building a generic NAPA cell file calling
  a C function, a C macro or a NAPA user function, it is a good
  practice to call the corresponding header explicitely to
  guarantee that this function is effectively compiled and linked
  to the executable when <toolbox.hdr> is not included by the user
  in the '.nap' simulation file.



  Example:

  ======================================================mycell.net===
  cell interface $out $in

  ...
  dvar $offset  rand_gaussian(3.0e-3)
  ...

  header <Function/random.hdr>     // contains 'rand_gaussian()' code

  ===================================================================