You're seeing just the function set_phx_attributes, go back to PhxComponentHelpers module for more information.
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set_phx_attributes(assigns, opts \\ [])

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Just a convenient method built on top of set_prefixed_attributes/3 for phx attributes. It will automatically detect any attribute prefixed by phx_ from input assigns. By default, the :into option of set_prefixed_attributes/3 is :phx_attributes


|> set_phx_attributes(required: [:phx_submit], init: [:phx_change])

assigns now contains @raw_phx_change, @raw_phx_submit and @raw_phx_attributes.