Returns the last value of a series.
last series
series - The series argument. (must be: series port tuple)
An error will occur if no value is found. Use the PICK function to avoid this error.
print last "REBOL" L
print last [11 22 33 44 55 66] 66
first - Returns the first value of a series.
pick - Returns the value at the specified position in a series.
tail - Returns the series at the position after the last value.
tail? - Returns TRUE if a series is at its tail.