''' Purpose: do some functions produces lists from a string
'''

def separate( s ) :
    ''' Returns a new list where each element in the list corresponds to a
        character of s
    '''

    # words = list(s) # Casting the string to a list (makes a list of characters from string s)
    # return words

    # Accumulator Way:
    new_list = []
    for ch in s:    # Loop through each character in the string s
        new_list.append( ch )   # Add each character to our list accumulator new_list
    return new_list     # Return the list accumulator new_list we built up by adding each character to it

    # Great problem solving pattern for function problems where we "return a new list" * KEY WORDING
    # ACCUMULATION PATTERN
    # new_list = []
    # Loop through a sequence
    # for ... in ... (usually sequence passed in):
        # new_list.append( what we wanna add )
    # return new_list

def ints( ns ) :
    ''' Returns list of integers corresponding to the integer substrings in ns.
    '''

    # Accumulator
    result = []     # same as doing new_list = []
    list_numeric_strings = ns.split()           # Break up the string of numbers into a list of numeric strings
    for numeric_string in list_numeric_strings: # Loop through each numeric string in the list of numeric strings
        number = int( numeric_string )          # Convert each numeric_string to an integer
        result.append( number )                 # Add each integer version of the numeric strings to the result list accumulator
    return result                               # Return final list of numbers from that string of numeric strings

# Ask yourself what we're returning and work up to building up and creating that result
# if we are returning a new list! ^

def parse_phone_string( pn ) : # String of a phone number
    ''' Returns a three-element integer list for string phone # pn:
           1st element: pn area code
           2nd element: pn prefix
           3rd element: pn line number
    '''

    # Get the digits from the string and then produce a list of the integers of the
    # area code, prefix, and line number

    digits = '0123456789'       # Define a string of digits (the numbers we want out of the string pn)
    numbers = ''                # Accumulator of only the numbers from the pn passed in
    for ch in pn:               # Loop through pn string passed in
        if ( ch in digits ):    # If the character is a number (if it's in the digits string)
            numbers = numbers + ch      # Add it to our numbers string
    # print( 'numbers =', numbers )

    # Break up the string numbers into the three parts of a phone number using slicing (getting characters in the
    # string at particular indices)
    area_code = numbers[ 0: 3 ] # numbers string at indices 0,1,2 (first three)
    prefix = numbers[ 3: 6 ] # numbers string at indices 3,4,5 (second three)
    line_number = numbers[ 6: 10 ] # numbers string at indices 6,7,8,9 (last four)

    # Alternate way that makes use of our function ints() above that converts a string of numbers to a list of numbers
    number = area_code + ' ' + prefix + ' ' + line_number
    result = ints( number ) # Use the function ints we defined above in the module
    return result

    # Another way of getting the number versions of the three parts without the ints() function:
    # Convert each string portion to an integer
    # area_code = int( area_code )
    # prefix = int( prefix )
    # line_number = int( line_number )
    # # List of the three integer parts
    # result = [ area_code , prefix , line_number ]
    # return result

    pass