import re


def is_float(text):
    '''Return whether the given string represents a float.'''
    return re.search(r'^-?\d+(\.\d+)?$', text) != None


def extract_names(text):
    '''Returns the first and last names of a full name as a 2-tuple'''
    match = re.search(r'^\s*([A-Z]\w*)\s+([A-Z]\w*)\s*$', text)
    if match != None:
        # yes, this is a match
        return (match.group(1), match.group(2) )
    else:
        print('This isn\'t a valid full name')
        return None
    
    
def find_long_words(filename, num_chars):
    '''Print all words in filename that are at least num_chars characters long.'''
    input_file = open(filename)
    text = input_file.read().lower()
    input_file.close()

    regex = r'\b[a-zA-Z]{' + str(num_chars) + r',}\b'
    words = re.findall(regex, text)
    
    for word in set(words):
        print(word)
        

def print_comments(filename):
    '''Print all the non-docstring comments in the Python program stored in filename.'''
    input_file = open(filename)
    for line in input_file:  # loop over the lines of file
        line = line.strip()
        match = re.search(r'#([^\']*)$', line)

        # simple version
#        match = re.search(r'#(.*)$', line)

        if match != None:
            # yes, this line has ' a comment
            print(match.group(1))

    input_file.close()