Line Dissolve
shapes_lines
QgsProcessingParameterFeatureSource|LINES|Lines|-1|None|False
QgsProcessingParameterField|FIELD_1|1. Attribute|None|LINES|-1|False|False
QgsProcessingParameterField|FIELD_2|2. Attribute|None|LINES|-1|False|False
QgsProcessingParameterField|FIELD_3|3. Attribute|None|LINES|-1|False|False
QgsProcessingParameterEnum|ALL|Dissolve...|[0] lines with same attribute value(s);[1] all lines
QgsProcessingParameterVectorDestination|DISSOLVED|Dissolved Lines