Constants can be: integer, floating point, string and date.
An Integer must begin with ['0'..'9']. For example, 16782
The floating point like 32.81e-4 or 12.8
Floating point values may not contain thousand seperators and are
internally converted to double precision floating point values.
The string must begin and end with quote ("). For example, "test string"
The date format is the same as your computers locale settings.