implement meta token replacement

language.toml

@@ -11,6 +11,7 @@ comments = ["^--.*", ""]
 with = ["^#with ([\\w./]+)", "cat $1"]
 date = ["#date_now", "date"]
 user = ["#user", "user"]
+test = ["#test", "cat ./mathlib.mlc"]
 
 # Describes tokens to be replaced by identifiers and then later swapped back in after the tokenizer.
 # All special tokens are treated as constants
@@ -28,7 +29,7 @@ operands = [":=", "->", "<=", ">=", "<", ">", "!", "+", "-", "/", "*", "(", ")",
 terminator = [";"]
 
 [semantics]
-keywords = ["if", "then", "else", "end", "with"]
+keywords = ["if", "then", "else", "end"]
 
 [constants]
 number = "(?:0b[01]+|0x[0-9a-fA-F]+|0[0-7]+|[1-9][0-9]*)"