Command line application this tool is called vert, and it converts between different units of temeperature.
It defines a set of options (flags) that determine the target temperature. and takes a list of positional arguments in the form {value}{symbol}.
vert -k 56c can be read as convert 56 degrees Celsius to Kelvin.
Note when using negative numbers: prefix the argument(s) with -- to indicate that what follows isn't a flag, if not the negative number will be interpreted as a flag by the program which raises an error. Read more here and here
