Examples: Added new syntax to python grammar

examples/advanced/python3.lark

@@ -23,7 +23,7 @@ decorated: decorators (classdef | funcdef | async_funcdef)
 async_funcdef: "async" funcdef
 funcdef: "def" NAME "(" parameters? ")" ["->" test] ":" suite
 
-parameters: paramvalue ("," paramvalue)* ["," [ starparams | kwparams]]
+parameters: paramvalue ("," paramvalue)* ["," "/"] ["," [starparams | kwparams]]
           | starparams
           | kwparams
 starparams: "*" typedparam? ("," paramvalue)* ["," kwparams]

lark/grammars/python.lark

@@ -6,11 +6,11 @@ COMMENT: /#[^\n]*/
 STRING : /[ubf]?r?("(?!"").*?(?<!\\)(\\\\)*?"|'(?!'').*?(?<!\\)(\\\\)*?')/i
 LONG_STRING: /[ubf]?r?(""".*?(?<!\\)(\\\\)*?"""|'''.*?(?<!\\)(\\\\)*?''')/is
 
-DEC_NUMBER: /0|[1-9]\d*/i
+DEC_NUMBER: /0|[1-9][\d_]*/i
 HEX_NUMBER.2: /0x[\da-f]*/i
 OCT_NUMBER.2: /0o[0-7]*/i
 BIN_NUMBER.2 : /0b[0-1]*/i
-FLOAT_NUMBER.2: /((\d+\.\d*|\.\d+)(e[-+]?\d+)?|\d+(e[-+]?\d+))/i
+FLOAT_NUMBER.2: /((\d+\.[\d_]*|\.[\d_]+)(e[-+]?\d+)?|\d+(e[-+]?\d+))/i
 IMAG_NUMBER.2: /\d+j/i | FLOAT_NUMBER "j"i