anchor.diff:  module test_helpers
   
     use iso_c_binding, only: c_double, c_bool
  -  use helpers, only: vector_close, in_interval
  +  use helpers, only: cross_product, vector_close, in_interval
     use types, only: dp
     implicit none
  -  private
  +  private test_cross_product, test_vector_close, test_in_interval
     public helpers_all_tests
   
   contains
  
positive.code:     vec2(1, :) = [0.0_dp, 0.0_dp]
      is_close = vector_close(2, vec1, vec2, eps)
      if (.NOT. is_close) then
         write (*, "(A)") "vector_close: Case 6 success"
      else
         write (*, "(A)") "vector_close: Case 6 failure"
         success = .FALSE.
      end if
  
  
negative.code:     vec2(1, :) = [1.0_dp, -4.0_dp]
      is_close = vector_close(2, vec1, vec2, eps)
      if (.NOT. is_close) then
         write (*, "(A)") " vector_close: Case 2 success"
      else
         write (*, "(A)") " vector_close: Case 2 failure"
         success = .FALSE.
      end if
  
  