procedure
A function to close the channel. Once closed, all channel identifiers referencing the channel are set to null.
If the channel is open for reading from or writing to a text file, an optional numeric parameter may be supplied. If this parameter is non-zero, the file will be deleted once the channel has been closed.
The code of the function cannot be redefined.
channel.close(<channel>)
The function may be called in one of two ways:
# Assume mychan is the channel identifier. channel.close(mychan)
or
mychan.close()