fn main() {
    a := 4 // comment1
     + 6 // comment2

    b := 5 + // comment3
     6

    c := 4 + 6 // comment4

    var := 'a' // comment5
     + 'b' // comment6
     + 'c' // comment7

    // vfmt off
pattern := r'^('
    + r'(\^|([<>]?=?))?'       // match: ^, >, <, =, >=, <=
    + r'((\*)|([0-9]+))'       // match: *, 1
    + r'((\.?\*)|(\.[0-9]+))?' // match: *, .*, .1
    + r'((\.?\*)|(\.[0-9]+))?' // match: *, .*, .1
    + r'(-[0-9a-zA-Z.]+)?)'    // match prerelease part e.g: -beta.1
    + r'|(\*)$'                // match just '*'
    // vfmt on

    pattern_fmt := r'^(' + r'(\^|([<>]?=?))?' // match: ^, >, <, =, >=, <=
     + r'((\*)|([0-9]+))' // match: *, 1
     + r'((\.?\*)|(\.[0-9]+))?' // match: *, .*, .1
     + r'((\.?\*)|(\.[0-9]+))?' // match: *, .*, .1
     + r'(-[0-9a-zA-Z.]+)?)' // match prerelease part e.g: -beta.1
     + r'|(\*)$' // match just '*'
}