prepending a button to a header

automatic_text_preferences2.py

import bpy


class SetTextPreferences(bpy.types.Operator):
    bl_label = ""
    bl_idname = "txt.set_text_prefs"
    
    def execute(self, context):
        st = context.space_data
        st.show_line_numbers = True
        st.show_word_wrap = True
        st.show_syntax_highlight = True
        st.show_margin = True
        return {'FINISHED'}


class TextHeaderAddition(bpy.types.Header):
    # bl_label = "Hello World Panel"
    # bl_idname = "OBJECT_PT_hello"
    bl_space_type = "TEXT_EDITOR"
    bl_region_type = "HEADER"
   
    def draw(self, context):

        layout = self.layout
        row = layout.row()
        row.operator("txt.set_text_prefs", icon='COLOR')


def register():
    bpy.utils.register_class(TextHeaderAddition)
    bpy.utils.register_class(SetTextPreferences)

def unregister():
    bpy.utils.unregister_class(TextHeaderAddition)
    bpy.utils.unregister_class(SetTextPreferences)

if __name__ == "__main__":
    register()