How does the `j` suffix for complex numbers work? Can I make my own suffix?

Question

I know what are complex numbers and how they mathematically work, but how is it done for python to know it's complex just by putting a j after a digit ?

>>> j
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
NameError: name 'j' is not defined
>>> 1*j
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
NameError: name 'j' is not defined
>>> 1j
1j
>>> 1j**2
(-1+0j)

Can I make my own suffix, let's say p (for strictly positive) ?

Could I do something working like this ?

>>> ... some weird stuff here ...
>>> p
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
NameError: name 'p' is not defined
>>> 1*p
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
NameError: name 'p' is not defined
>>> -1p
1p
>>> 0p
1p
>>> 

Answer 1

This is built into Python's grammar, just like the decimal point is, or the e in scientific notation (1e10 etc.). The j makes a numeric literal imaginary.

Python does not allow you to change this. That doesn't mean you can't--you could amend the grammar--but then the language is no longer Python.

The closest approximation allowed in Python would be by implementing an operator.

>>> class StrictlyPositive:
    def __rmatmul__(self, number):
        return abs(number)


>>> p = StrictlyPositive()
>>> -1@p
1

But you have to be careful of operator precedence when doing stuff like this. Why not just use the builtin abs directly?