anchor.diff:    key_mask(:,:) = key_in(:,:)
     key_mask(fh1/bit_kind_size + 1, fs1) -= 2**(mod(fh1-1,bit_kind_size))
     key_mask(fh2/bit_kind_size + 1, fs2) -= 2**(mod(fh2-1,bit_kind_size))
  -!   
  +
   !   do i=1,N_int
   !     n_alpha = n_alpha + popcnt(key_mask(i, 1))
   !     n_beta = n_beta + popcnt(key_mask(i, 2))
  
positive.code:   integer                               :: n_minilist, n_alpha, n_beta, deg(2), i, ni
    $declarations
    
    p1_mask(:,:) = 0
    p2_mask(:,:) = 0
    p1_mask(fh1/bit_kind_size + 1, fs1) = 2**(mod(fh1-1,bit_kind_size))
    p2_mask(fh2/bit_kind_size + 1, fs2) = 2**(mod(fh2-1,bit_kind_size))
    
  
negative.code:   
    logical :: check_double_excitation 
    
    key_mask(:,:) = 0_bit_kind
    
    iproc = iproc_in
  
  