def get_sentences(text):
    """ (str) -> list
    
    The function takes as input a string. It returns a list of strings
    each representing one of the sentences from the input string.
    
    >>> t = "No animal must ever kill any other animal. All animals are equal."
    >>> get_sentences(t)
    ['No animal must ever kill any other animal', 'All animals are equal']
    
    >>> t = "Hello! How are you? I'm doing fine, thank you."
    >>> get_sentences(t)
    ['Hello', 'How are you', "I'm doing fine, thank you"]
    
    >>> t = "A sentence without ending punctuation"
    >>> get_sentences(t)
    ['A sentence without ending punctuation']
    
    >>> t = "Hey!I am Groot.Who are you?" # no space behind punctuation
    >>> get_sentences(t)
    ['Hey', 'I am Groot', 'Who are you']
    
    >>> t = ""
    >>> get_sentences(t)
    []
    
    >>> t = " "
    >>> get_sentences(t)
    []
    """
    # initialize variables
    sentences = []
    start = 0
    
    # locate the punctuation that separates sentences
    # by iterating through each character
    for index in range(len(text)):
        if text[index] in ".!?":
            # add the sentence to the list of sentences
            sentence = text[start : index]
            if sentence != "":
                sentences.append(sentence.strip())
            # mark the start of the next sentence
            start = index + 1
    
    # in case the sentence does not have an ending punctuation
    if (len(text) >= 1) and (text[-1] not in ".!?\" "):
        sentences.append(text[start : ])

    # return the list of sentences
    return sentences