This class provides the base functionality for Excel sheet functions
There are two kinds of function Ptgs - tFunc and tFuncVar
Therefore, this class will have ONLY two subclasses
Appends all of the elements in the specified collection to the
end of this list, in the order that they are returned by the
specified collection's iterator.
Appends all of the elements in the specified collection to the
end of this list, in the order that they are returned by the
specified collection's iterator.
Adds a string to the SST table and returns its index (if its a duplicate
just returns its index and update the counts) ASSUMES compressed unicode
(meaning 8bit)
Returns the number of bytes that can be read (or skipped over)
from this input stream without blocking by the next caller of a
method for this input stream.