Get locals from calling namespace in Python

I want to retrieve the local variables from Python from a called function. Is there any way to do this? I realize this isn't right for most programming, but I am basically building a debugger. For example:

def show_locals():
  # put something in here that shows local_1.

local_1 = 123
show_locals()  # I want this to show local_1.

What do I put in the body of show_locals? If I have to modify the calling statement, what is the minimal modification I can make?

Note: this must work when show_locals is in a different module to its caller.

If you're writing a debugger, you'll want to make heavy use of the inspect module:

def show_callers_locals():
    """Print the local variables in the caller's frame."""
    import inspect
    frame = inspect.currentframe()
    try:
        print(frame.f_back.f_locals)
    finally:
        del frame

Perhaps it is worth pointing out that the technique from the accepted answer that reads from the caller's stack frame:

import inspect
def read_from_caller(varname):
    frame = inspect.currentframe().f_back
    try:
        v = frame.f_locals[varname]
        return v
    finally:
        del frame

can also write into the caller's namespace:

import inspect
def write_in_caller(varname, v):
    frame = inspect.currentframe().f_back
    try:
        frame.f_locals[varname] = v
    finally:
        del frame

If you put that in a module called "access_caller", then

import access_caller
access_caller.write_in_caller('y', x)

is an elaborate way of writing

y = x

(I am writing this as a fresh answer because I don't have enough reputation points to write a comment.)