count_words.py

def count_words(text):
    """Makes a statistic of the words appearing in the text 
       and returns a dictionary where keys are the words and 
       values are the number of occurrence of each word."""
    words = text.split()
    result = {}
    for word in words:        
        if word in result:
            result[word] += 1
        else:
            result[word] = 1

    return result


if __name__ == "__main__":
    text = """In computer programming, a string is traditionally a sequence of characters, either as a literal constant or as some kind of variable. The latter may allow its elements to be mutated and the length changed, or it may be fixed (after creation). A string is generally understood as a data type and is often implemented as an array of bytes (or words) that stores a sequence of elements, typically characters, using some character encoding. A string may also denote more general arrays or other sequence (or list) data types and structures. Source [Wikipedia http://en.wikipedia.org/wiki/String_(computer_science)]"""
    print("Text which will be checked: {0}".format(text))
    stat = count_words(text)
    for key in sorted(stat):
        print("[{0}] appeared {1} times.".format(key, stat[key]))

Awesome, was great help!