# How to get a Boolean from the type of an object?

I am trying to define the `__init__`

of a class, where I would like to support different types of input; in my case the input could be a either a list of pairs or a matrix. How do I write a Boolean function to test which kind of input I have? In the example code, I want to know how I should define the Boolean functions `is_a_matrix(A)`

and `is_a_tuple_of_pairs(A)`

(and of course more generally testing `A`

to be of some other type)

```
class someclass():
def __init__(self, A):
if is_a_matrix(A):
self._matrix = A
if is_a_tuple_of_pairs(A):
self._matrix = somefunction(A)
```