Exercise that I had to do in a live sharing-code interview

is_braces_balanced.py

def is_balanced(input_string):
    pending_braces = list()
    open_braces, closing_braces = '[{(', ']})'
    
    for c in input_string:
        if c in open_braces:
            index = open_braces.index(c)
            pending_braces.append(closing_braces[index])
            continue
        
        if c in closing_braces:
            last_brace = pending_braces.pop() if pending_braces else None
            
            if c != last_brace:
                return False
    
    return not pending_braces

# Test cases:
print is_balanced('[()]{}{[(())]()}')
print is_balanced('[(])')
print is_balanced(')[(])')