variables in python

scope.py

a, b, c = (1, 2, 3)

print(a, b, c)

def test():
    print(a)
    print(b)
    print(c)    # (A)
    c=1       # (B)
test()

"""for variable in python, you can see the variables in outer scope, but you 
can not edit it."""

"""
Although scopes are determined statically, they are used dynamically. At any time during execution, there are at least three nested scopes whose namespaces are directly accessible:

the innermost scope, which is searched first, contains the local names 
the scopes of any enclosing functions, which are searched starting with the nearest enclosing scope, contains non-local, but also non-global names 
the next-to-last scope contains the current module’s global names 
the outermost scope (searched last) is the namespace containing built-in names 
If a name is declared global, then all references and assignments go directly to the middle scope containing the module’s global names. Otherwise, all variables found outside of the innermost scope are read-only (an attempt to write to such a variable will simply create a new local variable in the innermost scope, leaving the identically named outer variable unchanged).

Usually, the local scope references the local names of the (textually) current function. Outside functions, the local scope references the same namespace as the global scope: the module’s namespace. Class definitions place yet another namespace in the local scope.
"""