instruction: Create a Dockerfile for fundamentals
output: ```dockerfile
  FROM busybox
  COPY hello.c ./
  EOFRemote tarballsIf you pass the URL to a remote tarball, the URL itself is sent to the builder.
  
  $ docker build http://server/context.tar.gz
  #1 [internal] load remote build context
  #1 DONE 0.2s
  
  #2 copy /context /
  #2 DONE 0.1s
  ...
  The download operation will be performed on the host where the BuildKit daemon
  is running. Note that if you're using a remote Docker context or a remote
  builder, that's not necessarily the same machine as where you issue the build
  command. BuildKit fetches the context.tar.gz and uses it as the build
  context. Tarball contexts must be tar archives conforming to the standard tar
  Unix format and can be compressed with any one of the xz, bzip2, gzip or
  identity (no compression) formats.Empty contextWhen you use a text file as the build context, the builder interprets the file
  as a Dockerfile. Using a text file as context means that the build has no
  filesystem context.You can build with an empty build context when your Dockerfile doesn't depend
  on any local files.How to build without a contextYou can pass the text file using a standard input stream, or by pointing at the
  URL of a remote text file.
  Unix pipe
  
  PowerShell
  
  Heredocs
  
  Remote file
  
  $ docker build - < Dockerfile
  
  Get-Content Dockerfile | docker build -
  
  docker build -t myimage:latest - <<EOF
  ```