module Padrino::Helpers::OutputHelpers

and implicitly concat.
can't take an <% end %> later on, so we have to use <% ... %>
We'd return a string in any other case, but erb <%= ... %>
Check whether we're called from an erb template.

def block_is_erb?(block)
  has_erb_buffer? || (block && eval('defined? __in_erb_template', block))
end