KT element: KtIsExpression
FIR element: FirTypeOperatorCallImpl
FIR source kind: KtRealSourceElementKind

FIR element rendered:
(x# is String)

FIR FILE:
FILE: [ResolvedTo(IMPORTS)] isExpressionScript.kts
    context(<script>@kotlin.script.templates.standard.ScriptTemplateWithArgs)
    SCRIPT: [ResolvedTo(BODY_RESOLVE)] 
        [ResolvedTo(RAW_FIR)] lval args: R|kotlin/Array<kotlin/String>|

        public? final? [ResolvedTo(RAW_FIR)] fun foo([ResolvedTo(RAW_FIR)] x: Any): Boolean {
            ^foo (x# is String)
        }