Element file

file =>

array:13 [
  "class" => "Drupal\Core\Render\Element\File"
  "provider" => "core"
  "id" => "file"
  "#input" => true
  "#multiple" => false
  "#process" => array:1 [
    0 => array:2 [
      0 => "Drupal\Core\Render\Element\File"
      1 => "processFile"
    ]
  ]
  "#size" => 60
  "#pre_render" => array:1 [
    0 => array:2 [
      0 => "Drupal\Core\Render\Element\File"
      1 => "preRenderFile"
    ]
  ]
  "#theme" => "input__file"
  "#theme_wrappers" => array:1 [
    0 => "form_element"
  ]
  "#value_callback" => array:2 [
    0 => "Drupal\Core\Render\Element\File"
    1 => "valueCallback"
  ]
  "#type" => "file"
  "#defaults_loaded" => true
]