For loop in function to move the item of the list

I want to move the negative numbers to the end of the list until I encounter the positive number.

List:

a=[-1,-2,2,3,4,-5]

The result i want:

[-2, 2, 3, 4, -5, -1]
[2, 3, 4, -5, -1, -2]

My function:

def f1(A):
  for i in A:
    if i>=0:
      break
    if 'Z' not in globals() or 'Z' not in locals():
     X=A
     X1=X[0]
     X.remove(X1)
     X.append(X1)
     Z=X 
    else:
      X=Z
      X1=X[0]
      X.remove(X1)
      X.append(X1)
      Z=X
    print(Z)
 
a=[-1,-2,2,3,4,-5]
print (f1 (a))

But the result

[-2, 2, 3, 4, -5, -1]
None

can we solve it with this function?

>Solution :

It’s not a for loop, but:

>>> def shift(lst):
...     while lst[0] < 0:
...         lst = lst[1:] + [lst[0]]
...     return lst
... 
>>> a
[-1, -2, 2, 3, 4, -5]
>>> b = shift(a)
>>> b
[2, 3, 4, -5, -1, -2]