module Kramdown::Parser::Html::Parser

def parse_html_attributes(str, line = nil, in_html_tag = true)

contain only lowercase letters.
If the optional +in_html_tag+ parameter is set to +false+, attributes are not modified to

If the optional +line+ parameter is supplied, it is used in warning messages.

Parses the given string for HTML attributes and returns the resulting hash. 
def parse_html_attributes(str, line = nil, in_html_tag = true)
  attrs = {}
  str.scan(HTML_ATTRIBUTE_RE).each do |attr, val, _sep, quoted_val|
    attr.downcase! if in_html_tag
    if attrs.key?(attr)
      warning("Duplicate HTML attribute '#{attr}' on line #{line || '?'} - overwriting previous one")
    end
    attrs[attr] = val || quoted_val || ""
  end
  attrs
end