initialize two more struct Tree members to appease coverity scan

    int nvector;           // length of array for vector-style variable

    int nstride;           // stride between atoms if array is a 2d array

    int selfalloc;         // 1 if array is allocated here, else 0

    int ivalue1,ivalue2;   // extra values for needed for gmask,rmask,grmask

    int ivalue1,ivalue2;   // extra values needed for gmask,rmask,grmask

    int nextra;            // # of additional args beyond first 2

    Tree *first,*second;   // ptrs further down tree for first 2 args

    Tree **extra;          // ptrs further down tree for nextra args

    Tree() :

      array(NULL), iarray(NULL), barray(NULL),

      selfalloc(0), nextra(0),

      first(NULL), second(NULL), extra(NULL)

    {

    }

      selfalloc(0), ivalue1(0), ivalue2(0), nextra(0),

      first(NULL), second(NULL), extra(NULL) {}

  };

  int compute_python(int);