identify_symbols.py

def identify_symbols(string):
    elements = []
    num_stack = [] # holds numbers
    index = 0
    while index < len(string):
        char = string[index]
        if char in '+-/*()':
            # Add number to elements
            if num_stack:
                elements.append(''.join(num_stack))
                num_stack = []
                
            if (char in '+-/*'):
                if (char == '*' and string[index+1] == '*'):
                    elements.append('**')
                    index += 1
                else:
                    elements.append(char)
            elif char == '(': 
                elements.append('(')
            elif char == ')':
                elements.append(')')
        elif char in '0123456789':
            num_stack.append(char)
        index += 1
    # If numbers remain on the stack
    if num_stack:
        elements.append(''.join(num_stack))
        num_stack = []
    return elements
    
print(identify_symbols('111+2+(33**2)-1*1'))
# ['111', '+', '2', '+', '(', '33', '**', '2', ')', '-', '1', '*', '1']