/**
 * Strip backticks from a 0.x program source so it parses under the unified
 * 1.x grammar. Backticks were the membrane between the dice expression
 * sublanguage and the program language; the unified parser folds both into
 * one grammar, and the parser now rejects backticks with a clear error.
 *
 * `migrateSource` is a one-line regex helper: it removes every backtick
 * character. It does not validate the result — pipe the output to
 * `ProgramParser.parse` to confirm the migrated source compiles.
 *
 * Example:
 * ```ts
 * import { migrateSource, ProgramParser } from 'dicerollerts'
 * const oldSrc = '$atk = `d20 + $str`\n$atk'
 * const newSrc = migrateSource(oldSrc)  // '$atk = d20 + $str\n$atk'
 * const result = ProgramParser.parse(newSrc)
 * ```
 *
 * Safe to call on already-migrated source: with no backticks present the
 * input is returned unchanged.
 */
export declare function migrateSource(source: string): string;