Symbols

	In order to be able to make the transition from tokens to AST, the 
	parser needs to be able to recognize functions, variables, types, etc. 
	The symb module keeps track of all these symbols and their namespaces 
	and scopes. The parser can do lookups in the current scope, or in just 
	specific namespaces. Many AST nodes have a corresponding symbol (e.g. 
	variables and functions). 

