Harvard cs50 convert to camel case review please

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I have been going through the harvard cs50 problems, and just did the convert to camel case problem. I did go a step beyond and made it convert from snake to camel and camel to snake based on what what inputed. Can anyone review it for me and see if there is a better way to do anything?

#get variable
def main():
    variable = input('What variable do you want to convert?')
    type = camel_case_check(variable)

    if type == 'nothing':
        print('The variable does not need converting')
    elif type == 'camel':
        print('The variable is converting to snake case')
        print(convert_to_snake(variable))
    elif type == 'spaces':
        print('The variable has spaces, please remove the spaces and try again')
    else:
        print('The variable is converting to camel case')
        print(convert_to_camel(variable))
#check if its camel case or snake case
def camel_case_check(variable):
    if variable.count(' '):
        return 'spaces'
    if variable.count('_') == 0:
    
        for letter in variable:
            if letter.isupper():
                return 'camel'
        
        return 'nothing'
    
    return 'snake'

#convert to opposite case
def convert_to_snake(variable):
    new_variable = ''
    for letter in variable:
        if letter.islower():
            new_variable = new_variable + letter
        else:
            letter = letter.lower()
            new_variable = new_variable + '_' + letter

    return new_variable

def convert_to_camel(variable):
    new_variable = ''
    underscore_count = 0
    
    for letter in variable:
        if letter == '_':
            underscore_count +=1
        elif underscore_count == 1:
            new_variable = new_variable + letter.upper()
            underscore_count = 0
        else:
            new_variable = new_variable + letter
    
    return new_variable

            
if __name__ == '__main__':
    main()