How to use the metro-source-map/src/Consumer/search.greatestLowerBound function in metro-source-map

function findOriginalPos(
    frame: StackFrameInput,
    module: ExplodedSourceMapModule,
  ): ?Position {
    if (
      module.map == null ||
      frame.lineNumber == null ||
      frame.column == null
    ) {
      return null;
    }
    const generatedPosInModule = {
      line1Based: frame.lineNumber - module.firstLine1Based + 1,
      column0Based: frame.column,
    };
    const mappingIndex = greatestLowerBound(
      module.map,
      generatedPosInModule,
      (target, candidate) => {
        if (target.line1Based === candidate[0]) {
          return target.column0Based - candidate[1];
        }
        return target.line1Based - candidate[0];
      },
    );
    if (mappingIndex == null) {
      return null;
    }
    const mapping = module.map[mappingIndex];
    if (
      mapping[0] !== generatedPosInModule.line1Based ||
      mapping.length < 4 /* no source line/column info */

function findModule(frame: StackFrameInput): ?ExplodedSourceMapModule {
    const map = mapsByUrl.get(frame.file);
    if (!map || frame.lineNumber == null) {
      return null;
    }
    const moduleIndex = greatestLowerBound(
      map,
      frame.lineNumber,
      (target, candidate) => target - candidate.firstLine1Based,
    );
    if (moduleIndex == null) {
      return null;
    }
    return map[moduleIndex];
  }