code: public SDVariable shape(String name, SDVariable input) {
          SDVariable ret = f().shape(input);
          return updateVariableNameAndReference(ret, name);
      }
docs: Returns the shape of the specified SDVariable as a 1D SDVariable
  
  @param name  Name of the output variable
  @param input Input variable
  @return 1D output variable with contents equal to the shape of the input