readline reads the next line from an open file and returns it as a string. Calling it again advances to the following line, making it useful for inspecting headers and individual records. section 5.1.4
Inspecting an NFL statistics file
After opening nfl_offensive_stats.csv, call line = nfl_file.readline() to retrieve its header. Split the string with line.split(',') to inspect column names, then call readline again to retrieve the first data row. Use a for loop instead when processing the entire file, and close the file afterward. section 5.1.4
