argument_index is an integer indicating position of the argument in the list. The first argument is referenced by "1$", the second by "2$", etc.
flags is a set of characters that modify the output format
width is a decimal integer indicating the minimum number of characters to be written to the output
precision is a decimal integer usually used to restrict (by rounding) the number of digits after decimal point
The required conversion is a character indicating how the argument should be formatted:
