import re


def clean(sentence):
    """Clean the text."""
    punctuation_spacer = str.maketrans({key: f"{key} " for key in ".,"})
    
    lower_sentence = sentence.lower()
    # Change `and/or` to `or`.
    corrected_sentence = re.sub('and/or',
                              'or',
                              lower_sentence)
    # Change any `XXX/YYY` to `XXX or YYY`.
    corrected_sentence = re.sub('(?<=[a-zA-Z])/(?=[a-zA-Z])',
                              ' or ',
                              corrected_sentence)
    # Clean double periods
    clean_sentence = corrected_sentence.replace("..", ".")
    # Insert space after commas and periods.
    clean_sentence = clean_sentence.translate(punctuation_spacer)
    # Convert any multi white spaces to single white spaces.
    clean_sentence = ' '.join(clean_sentence.split())

    return clean_sentence