converting individual digits to string

Question

I think i\'m very close but i cant seem to fix my issues. I need a function that takes a 10-digit input from user (me) and sets each letter to is numeric value.

Example:

Answer 1

phone_number = '941-019-aBcD'

# A map of what letters to convert to what digits.
#  I've added q and wxy & z.
digit_map = {
    'abc': 2,
    'def': 3,
    'ghi': 4,
    'jkl': 5,
    'mno': 6,
    'pqrs': 7,
    'tuv': 8,
    'wxyz': 9
}

# Break this out into one letter per entry in the dictionary
#  to make the actual work of looking it up much simpler.
#  This is a good example of taking the data a person might
#  have to deal with and making it easier for a machine to
#  work with it.
real_map = {}
for letters, number in digit_map.iteritems():
    for letter in letters:
        real_map[letter] = number

# Empty new variable.
numeric_phone = ''
# For each character try to 'get' the number from the 'real_map'
#  and if that key doesn't exist, just use the value in the
#  original string. This lets existing numbers and other
#  characters like - and () pass though without any special
#  handling.
# Note the call to `lower` that converts all our letters to
#  lowercase. This will have no effect on the existing numbers
#  or other speacial symbols.
for ch in phone_number.lower():
    numeric_phone += str(real_map.get(ch, ch))

print(numeric_phone)