class_docstr: Computes a Sankey diagram from a Graph element for internal use in
  the Sankey element constructor.
  
  Adapted from d3-sankey under BSD-3 license.
  
  Source: https://github.com/d3/d3-sankey/tree/v0.12.3
class_docstr_tok: ["Computes","a","Sankey","diagram","from","a","Graph","element","for","internal","use","in","the","Sankey","element","constructor",".","Adapted","from","d3-sankey","under","BSD-3","license",".","Source",":","https",":","\/\/github.com\/d3\/d3-sankey\/tree\/v0.12.3"]
code: def resolveCollisionsTopToBottom(cls, nodes, y, i, alpha, py):
      for node in nodes[i:]:
          dy = (y - node["y0"]) * alpha
          if dy > _Y_EPS:
              node["y0"] += dy
              node["y1"] += dy
          y = node["y1"] + py
  
imports: import math
  from functools import cmp_to_key
  from itertools import cycle
  import numpy
  import param
  from ..core.data import Dataset
  from ..core.dimension import Dimension
  from ..core.operation import Operation
  from ..core.util import get_param_values, unique_array
  from .graphs import EdgePaths, Graph, Nodes
  from .util import quadratic_bezier
label_desc: Use image node_id 15 for calling the _layout_sankey obj's underlying member method code with example usage: obj.resolveCollisionsTopToBottom(cls, nodes, y, i, alpha, py) without return types