core.js
function assertPart(part, name) {
  if (part.indexOf(path.sep) !== -1) {
    throw new Error(
      '`' + name + '` cannot be a path: did not expect `' + path.sep + '`'
    )
  }
}
function assertPart(part, name) {
  if (part.indexOf(path.sep) !== -1) {
    throw new Error(
      '`' + name + '` cannot be a path: did not expect `' + path.sep + '`'
    )
  }
}
function assertPart ( part , name ) { if ( part . indexOf ( path . sep ) !== - 1 ) { throw new Error ( '`' + name + '` cannot be a path: did not expect `' + path . sep + '`' ) } }
Assert that `part` is not a path (i.e., does not contain `path.sep`).
Assert that part is not a path ( i . e . does not contain path . sep ) .