Following the comments on the answer here I would like to know if there is a way to deduce from the documentation if a built-in expression is a function or simply "a variable that stores something".
For the motivation you can look here: without knowing if object are wrapper or not it would have been impossible for me to know that First[ContourPlot] gives the good variable to provide to Epilog for instance.
For instance, looking at the docs for graphics, it is not possible to understand that "primitives" and "options" are not parameter to provide to the function "Graphics" but actually what is stored in a Graphics type variable.
I find the documentation extremly confusing to learn, which is why I ask my question.
Thus, my question is precisely:
- Is there a way from the documentation to know if the expression is a function or a variable storing something
- If not, can I use some way in Mathematica to know it