LCCN normalization (https://www.loc.gov/marc/lccn-namespace.html#normalization) 1. Remove all blanks. 2. If there is a forward slash (/) in the string, remove it, and remove all characters to the right of the forward slash. 3. If there is a hyphen in the string: a. Remove it. b. Inspect the substring following (to the right of) the (removed) hyphen. Then (and assuming that steps 1 and 2 have been carried out): 1. All these characters should be digits, and there should be six or less. (not done in this function) 2. If the length of the substring is less than 6, left-fill the substring with zeroes until the length is six.