code: function main(opt) {
      var t = opt.types
      var template = opt.template
  
      return {
          manipulateOptions: function (rp) {
              var resolveModuleSource = rp.resolveModuleSource
              resolve =  resolveModuleSource || defaultResolve
          },
  
          visitor: {
              ImportDeclaration: {
                  exit: function (curPath, state) {
                      var opts = state.opts
                      var file = state.file
  
  
                      var importPath = curPath.node.source.value
                      var jsFilename = file.opts.filename
  
                      if (importPath.endsWith('.css')) {
                          const env = process.env.BABEL_ENV || process.env.NODE_ENV || 'development'
                          if (env === 'development') {
                              devHandler(curPath, importPath, jsFilename)
                          } else {
                              prodHandler(curPath, opts, importPath, jsFilename, template, t)
                          }
                      }
                  }
              }
          }
      }
  }
docs: React native can’t use the Webpack loaders, this plugin to make .css files importable in RN.
  In addition, we made some improvements to improve the runtime performance
  @param opt
  @returns