private SyntaxNode readNode()
{
if (currentCharacterStream.isNextCharDigit())
{
return(readNumber());
}
else if (currentCharacterStream.isNextCharEuler())
{
return(readEuler());
}
else if (currentCharacterStream.isNextCharVariable())
{
return(readVariable());
}
else
{
throw new UnknownSymbolException("Unrecognized Symbol " + currentCharacterStream.readAsString());
}
}