# accessing the materials
material = bpy.data.materials.get("Material")
# accessing all the nodes in that material
nodes = material.node_tree.nodes
# you can find the specific node by it's name
noise_node = nodes.get("Noise Texture")
# available inputs of that node
# print([x.identifier for x in noise_node.inputs])
# ['Vector', 'W', 'Scale', 'Detail', 'Distortion']
# change value of "W"
noise_node.inputs.get("W").default_value = 1