Given a color object, this function writes a file containing the hexadecimal
representation of the colors in the object.
Usage
writehex(x, file = "")
Arguments
x
a color object.
file
the name of the file to be written.
Value
The name of the file is returned as the value of the function.
Details
This function converts the given color object to RGB and then writes
hexadecimal strings (of the form #RRGGBB) representing the colors to
the specified file.