Net::HTTPHeader#initialize_http_header

# File tmp/rubies/ruby-3.1.3/lib/net/http/header.rb, line 13
def initialize_http_header(initheader)
  @header = {}
  return unless initheader
  initheader.each do |key, value|
    warn "net/http: duplicated HTTP header: #{key}", uplevel: 3 if key?(key) and $VERBOSE
    if value.nil?
      warn "net/http: nil HTTP header: #{key}", uplevel: 3 if $VERBOSE
    else
      value = value.strip # raise error for invalid byte sequences
      if value.count("\r\n") > 0
        raise ArgumentError, "header #{key} has field value #{value.inspect}, this cannot include CR/LF"
      end
      @header[key.downcase.to_s] = [value]
    end
  end
end