code: public long[] getShapeForVarName(String varName) {
          if (arrayAlreadyExistsForVarName(varName)) {
              return getVariable(varName).getArr().shape();
          }
          return variableNameToShape.get(varName);
      }
docs: Get the shape for the given vertex id.
  Note that if an array is defined, it will use the shape of the array instead.
  <p>
  A shape *and* an array should not be defined at the same time.
  This wastes memory. The internal map used for tracking shapes for particular
  vertex ids should also delete redundant shapes stored to avoid redundant sources of information.
  
  @param varName the vertex id to get the shape for
  @return the shape for the given vertex if any.